Continuous Queries in Spatio-temporal Databases

A continuous query is a new query type that is issued once and is evaluated continuously in a database server until the query is explicitly terminated. The most important characteristic of continuous queries is that their query result does not only depend on the present data in the databases but also on continuously arriving data. During the execution of a continuous query, the query result is updated continuously when new data arrives. Continuous queries are essential to applications that are interested in transient and frequently updated objects and require monitoring query results continuously. Potential applications of continuous queries include but are not limited to real-time location-aware services, network flow monitoring, online data analysis and sensor networks